Certain drugs can be extracted from natural sources, and this has been known for a long time. The ancient Greeks, for example, used willow bark to treat fevers and pains. Salicylic acid was later discovered to be the active ingredient. Chemists modified this to create aspirin, which is less irritating to the stomach than salicylic acid. Another example is digitalis, a heart drug derived from foxgloves.
Plants are still important today, but most drugs are now developed in laboratories by pharmaceutical company scientists. These companies now have synthetic versions of plant extracts that they use as a starting point for developing new drugs.
